I heard you dont have to re-jet your raptor if you use a HMF Slip On pipe....but do you have to re-jet if you put on a K&N Air Filter?

 

no answers guys?

 

I think you would need to jet up with either one, you are flowing more air, so you need more fuel. You could try it without jetting, but I'm sure you would be running lean. If you are spending money on a pipe you might as well get it running to its full potential, plus you are risking engine damage if its too lean.

 

It's not so much changing your filter but if you mod your air box or exhaust you'll need to rejet.

 

What's your altitude ? - that's important. If you are +1500 ft I'll bet you should be able to avoid re-jetting with just a slip-on. At sea level probably re-jet to be safe.